This invention relates to guide bars for guiding saw chains in a chain saw and more particularly to the auxiliary use of the bars for dispensing treatment fluid to the stump and/or tree as the tree is being severed from the stump.
It has been determined that a freshly cut tree stump is vulnerable to the growth of fungus that can be damaging to the future growth of adjacent trees and seedlings. To avoid such fungus growth, governments have regulated that freshly cut tree stumps are to be treated with an anti-fungus solution, e.g., urea.
It has been further determined that a preferred manner for applying the anti-fungus treatment, particularly when harvesting the trees using a tree harvester, is to equip the chain saw of the tree harvester with the means for dispensing the fluid onto the stump as the tree trunk is being cut from the stump.
Accordingly, chain saws have been developed whereby a fluid passage or channel is provided along the length of a guide bar of a chain saw, dispensing orifices are provided along the length of the channel and a source of treatment fluid is connected to the channel for injecting the fluid into the channel and through the orifice and onto a tree stump as the tree is being felled. Such a system is disclosed in U.S. application for patent Ser. No. 09/871,299 filed May 30, 2001 and which is commonly owned with the present invention.
The above explanation is somewhat misleading in the suggested simplicity of the system. It is desirable that the exposed sawn surface of the stump be evenly and completely treated with the fluid while avoiding excessive over spray, i.e., spray of the treatment fluid onto the vegetation and ground surrounding the tree stump. The chain saw of a tree harvester cuts through a tree by first centering the tree relative to the guide bar length and then pivoting the guide bar and cutting chain mounted thereon through the tree. If the bar is set up to cut large diameter trees, the dispensing orifices are extended substantially the full length of the bar and when cutting small diameter trees, there is excessive and undesired over spray. When set up to cut small diameter trees, as larger trees are encountered the spray will not be applied to the inner and outer reaches of the exposed surface, also undesired. Furthermore, due to the pivoting action of the chain saw, and thus the pivotal sweeping of the guide bar and saw chain through the tree (See FIG. 1), the inner length of the bar is exposed to a smaller portion of the stump surface than the outer length. This also contributes to uneven dispensing of the treatment fluid onto the stump.
From the above, it will be appreciated that the positioning of the orifices along the fluid channel is important. Manufacturers have addressed the problem of orifice size and location and have developed patterns of orifice sizes and spacing along the length of the bar. The patterns will not be further explained except to point out that the patterns may change between manufacturers of the guide bars and as between different sizes of trees being cut. Accordingly, it is presently considered desirable that the hole patterns be provided by the guide bar manufacturer to achieve optimum treatment of the stumps during felling.
The above is, however, incompatible with a problem that arises in providing invertible guide bars which are typical to the industry. As mounted on a chain saw, the leading edge of the bar is subjected to the cutting action and thus endures the greatest wearing. This is commonly countered by configuring the bar so that either edge can be mounted as the leading edge. This requires a symmetrical design of mounting slots and holes in the guide bar in general. Thus, when the initial leading edge of a bar becomes worn, the bar is simply inverted, the top becomes the bottom and the leading edge becomes the trailing edge. Yet the dispensing of the treatment fluid is confined to the bottom of the bar and it is not desirable to spray the freshly sawn surface of the severed tree. This, too, has been countered by placing a separate channel at each side of the guide bar. Only the channel that includes orifices open to the bottom side is connected to the source of the treatment fluid and the bar presumably now functions equally when inverted. This presumption is, however, incorrect as the unused orifices are subject to plugging as will be explained.
Heretofore bars have been produced having channels at both sides and the desired pattern of orifices is provided for in each of the channels. The concept was that the bar could be inverted when the one side becomes worn and the bar could be placed back in service to effectively double its wear life. However, what would often happen is that the operator would continue the cutting operation for some period of time before it was discovered that there was no treatment fluid being dispensed on the stumps being cut.
What was happening was that the holes or orifices of the unused channel, not being cleared by the emission of fluid, were being plugged with dirt, tree pitch and the like as the bar was forced through the tree. By the time the bar was inverted, the orifices were totally plugged and not easily unplugged. The operator could poke a pointed tool into the holes to clear the holes but such merely pushed the debris into the channel to plug the channel.
The only solution appeared to be to not provide the orifices in the secondary side of the bar and allow the operator to pierce the channel when he inverted the bar to the second bar side. However, experience with this practice has shown that an acceptable distribution of the treatment of the stump is not achieved if hole location is left to the devices of the tree harvester operator.
The present invention solves this problem by predetermining the desired hole pattern for the xe2x80x9cotherxe2x80x9d side, preferably providing a tool that would produce the desired hole size and then marking the xe2x80x9cotherxe2x80x9d bar side and preferably the channel wall itself whereat the orifices are to be placed. Even further, the marking can consist of indentations in the channel wall at the desired positions and the operator need only to position the tool in each indentation and then tap the tool to puncture a hole into the channel.